Tomatoes are usually to blame! If you wash your bowls alongside pans or bowls that have had strong coloured sauces in, like tomato or carrot, some of the colour can transfer. This can happen in the sink as well as the dishwasher. To keep your bowls looking lovely and new, put them at the front of the queue if you’re washing up by hand, and on the top shelf if you’re using a dishwasher. This usually results in fewer undesirable stains!